EP0009350A1

EP0009350A1 - Scroll-type fluid compressor units

Info

Publication number: EP0009350A1
Application number: EP79301808A
Authority: EP
Inventors: Kiyoshi Terauchi
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 1978-09-04
Filing date: 1979-09-03
Publication date: 1980-04-02
Also published as: EP0009350B1; US4314796A; CA1126708A; AU530176B2; AU5050579A; DE2966408D1

Abstract

A scroll-type refrigerant compressor unit has a drive shaft (17) supported in a front end plate (11) of a housing by a single radial bearing (16), and a disk rotor (21) having a drive pin (23) to effect orbital motion of an orbiting scroll member (24) is fixedly mounted on an inner end of the drive shaft and is supported on the front end plate by a thrust bearing (22). The orbiting scroll member (24) has an axial boss (243) which is rotatably mounted on the drive pin by means of a second radial bearing (26) and a radial flange (271) which is supported by a second thrust bearing (28) on the rear surface of the disk rotor. The unit is assembled by inserting parts into the compressor housing in a predetermined order and by finally securing a front end plate onto the compressor housing by bolts, whereby the production of the compressor unit is simplified. The drive shaft and, therefore, the compressor unit are made of reduced length and deflection and vibrations of the drive shaft are securely prevented. A lubricating system is provided to lubricate a shaft seal assembly on the drive shaft, whereby the oil in the compressor housing is directed to the shaft seal cavity (181) and returns to the interior of the compressor housing after lubricating the radial and thrust bearings and other parts. A mechanism for automatically reducing the compressed fluid amount at an increased high speed operation of the compressor unit is provided.

Description

This invention relates to scroll type fluid compressor units.
A scroll type apparatus has been well known in the prior art as disclosed in, for example, U.S. Patent No. 801,182, and others, which comprises two scroll members each having an end plate and a spiroidal or involute spiral element. These scroll members are so maintained angularly and radially offset that both of spiral elements interfit to make a plurality of line contacts between spiral curved surfaces thereby to seal off and define at least one fluid pocket. The relative orbital motion of these scroll members shifts the line contacts along the spiral curved surfaces and, therefore, the fluid pocket changes in volume. The volume of the fluid pocket increases or decreases in dependence on the direction of the orbital motion. Therefore, the scroll-type apparatus is applicable to handle fluids to compress, expand or pump them.
In comparison with conventional compressors of a piston type, a scroll-type compressor has some advantages such as less number of parts, continuous compression of fluid and others. But, there have been several problems; primarily sealing of the fluid pocket, wearing of the spiral elements, and inlet and outlet porting.
Although there have been many patents, for example, U.S. Patents Nos. 3,884,599, 3,924,977, 3,994,633, 3,994,636, and 3,994,635 in order to resolve those and other problems, the resultant compressor is complicated in the construction . and in the production. Furthermore, since a plurality of spaced radial bearings are used for supporting a drive shaft, the axial length of the drive shaft is increased so that the resultant compressor is increased in the entire length, in the volume and in the weight.
In the compressor of this type, lubricating system is also required for lubricating moving parts.
Since the compressor of this type is compact and light, it is advantageously used for a refrigerant compressor of an air conditioning for an automobile. However, if the automobile engine is used for a drive power source of the compressor, the compressor is driven at various speed in dependence of the rotational number of the automobile engine. Therefore, the compressed fluid amount discharged during a unit time at a time when the rotational number of the automobile engine is, for example, 5,000 r.p.m., is much more than that at a time when. the rotation number of the automobile engine is 1,000 r.p.m. Such a large variation of the compressed fluid amount is not desired for a refrigerant circulating circuit to be connected to the compressor.
It is an object of this invention to provide a compressor unit of a scroll type which has excellent sealing and anti-wearing properties and simple porting.
According to the present invention there is provided a scroll-type fluid compressor unit comprising a compressor housing having a front end plate and a rear end plate, a fixed scroll member fixedly disposed within said compressor housing and having first end plate means to which first wrap means are affixed and an orbiting scroll member orbitably disposed within said compressor housing and having second end plate means to which second wrap means are affixed, said first and second wrap means interfitting at a predetermined angular relationship to make a plurality of line contacts to define at least one sealed off fluid pocket which moves with reduction of volume thereof by the orbital motion of said orbiting scroll member, thereby to compress the fluid in the pocket, wherein a drive shaft is supported by first radial bearing means in said front end plate and extends outwardly through said front end plate, a disk rotor member is mounted on an inner end of said drive shaft and is supported by first thrust bearing means on an inner surface of said front end plate, a drive pin projeets axially on a rear surface of said disk rotor member and is radially offset from said drive shaft, said orbiting scroll member is provided with an axial boss which is formed on a surface of said second end plate member opposite to said second wrap means and is rotatably mounted on said drive pin which is fitted into said boss through second radial bearing means, a radial flange member is radially extending and is disposed at the projecting end of said axial boss and is supported by second thrust bearing means on the rear surface of said disk rotor member, and means are provided for preventing the rotation of said orbiting scroll member, but permitting the orbital movement of said orbiting scroll member. Preferably, the drive shaft axis and other moving parts axes are securely prevented from deflecting during the operation, there is an improved lubricating system for moving parts, and means are provided for permitting compressed fluid to leak from compressing fluid pockets at a high speed operation of the compressor unit.
Suitably, the rotation preventing means comprises a hollow member having a rectangular outer contour and non-rotatably fitted onto the axial boss, a slider member being fitted on the hollow member slidably in a first radial direction and having a rectangular hole and a rectangular outer contour with four sides being parallel to respective four sides of the rectangular hole, a first pair of parallel sides of the rectangular hole being equal in the length to a pair of parallel sides of the outer rectangle of the hollow member while the other second pair of parallel sides being longer than the other pair of parallel sides of the hollow member so that the slider member may be slidable on the hollow member along the second pair of parallel sides, and a guide member non-rotatably disposed within the housing and having guide surfaces for respective parallel outer surfaces of the slider member in parallel with the first pair of parallel sides to permit the movement of the slider member in a second radial direction perpendicular to the first radial direction, thereby to permit the orbital motion, but prevent the rotation, of the orbiting scroll member.
Preferably, the rear end plate of the compressor housing is provided with a fluid outlet port, and a first annular wall axially projecting on the inner surface of the rear end plate around the fluid outlet port. The fixed scroll member is provided with a fluid discharge port at a center of the first end plate means. A second annular wall axially projects on a surface of the first end plate means opposite to the first wrap means around the fluid discharge port. The first and second annular walls are fitted into one another to define a chamber therein. A sealing ring member of elastic materials is compressedly fitted into a gap between the first and second annular walls, thereby to seal off the chamber from an annular chamber portion surrounding the fitted annular walls and axially and radially elastically suport the fixed scroll member.
^I In the arrangement of the compressor unit, the sealing ring member, fixed and orbiting scroll members, rotation preventing means, radial flange member, second radial bearing means, second thrust bearing means, and a pre-assembly of drive pin, disk rotor member, first thrust bearing heans, first radial bearing means, drive shaft, and front end plate, are inserted in this order into the compressor housing, and the compressor unit is easily completed by securing the front end plate onto the compressor housing.
The compressor unit may comprise an oil deflector depending from the inner wall of the compressor housing thereinto. The front end plate is then provided with a shaft seal cavity around the drive shaft, and is formed with an oil opening disposed adjacent the oil deflector and with a first passageway therein for effecting communicate between the oil opening and the shaft seal cavity. A second passageway is formed to extend through the drive shaft and the drive pin, and effect communicate between the shaft seal cavity and the hollow space of the boss. Therefore, the lubricating oil of the inner wall of the compressor housing is directed by the deflector through the oil opening and into the shaft seal cavity. The oil in the shaft seal cavity partially flows along the drive shaft lubricating the first radial bearing means and, then, flows through the gap between the front end plate and the disk rotor member to lubricate the first thrust bearing means. The remainder flows through the second passageway into the hollow space of the boss to lubricate the second radial and thrust bearing means.
A fluid inlet port may be formed in the rear end plate for introducing refrigerant gas into the interior of the compressor housing therethrough. An oil separating plate nember may then be fixedly disposed in front of the inlet port. The oil mixed with the refrigerant gas strikes against, and attaches to, the oil separating plate member and is separated from the refrigerant gas to flow down along the plate.
The second end plate means of the orbiting scroll member may be provided with a round depression in a surface thereof opposite to the second wrap means and a small aperture at the center of the round depression. A ball is received in the round depression to close the aperture. Spring means is provided to urge the ball in the round depression at center thereof. Thus, when the compressor is driven at an increased high speed, the ball is displaced from the center of the round depression to open the aperture. So that the compressed gas in moving fluid pockets leaks in the interior of the compressor housing. Therefore, the compressed gas amount during a unit time is decreased and, therefore, is not so different from that at a time when the compressor is driven at a lower speed.
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

Fig. 1 is a vertical sectional view of a compressor unit of a scroll type according to an embodiment of this invention;
Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1;
Figs. 3a-3d are schematic views for illustrating movement of interfitting spiral elements to compress fluid;
Fig. 4 is a vertical sectional view of a main part of another embodiment of this invention;
Fig. 5 is a vertical sectional view of a main part of still another embodiment of this invention;
Fig. 6 is a front view of a head block used in the embodiment in Fig. 5;
Fig. 7 is a vertical sectional view of a further embodiment of this invention;
Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 7; and
Fig. 9 is a sectional view of a modification of the embodiment of Fig. 7.

Referring to Fig. 1, a refrigerant compressor unit 10 of an embodiment shown includes a compressor housing comprising a front end plate 11, a rear end plate 12 and a cylindrical body 13 connecting between those end plates. The rear end plate 12 is shown formed integrally with-the cylindrical body and is provided with a fluid inlet port 14 and a fluid outlet port 15 formed therethrough. A drive shaft 17 is rotatably supported by a radial needle bearing 16 in the front end plate 11. The front end plate 11 has sleeve portion 18 projecting.on the front surface thereof and surrounding the drive shaft 17 to define a shaft seal cavity 181. Within the shaft seal cavity, a shaft seal assembly 19 is assembled on drive shaft 17. A pulley 20 is rotatably mounted on sleeve portion 18 and is connected with drive shaft 17 to transmit an external drive power source (not shown) to drive shaft 17 through belt means (not shown) wound around the pulley 20. A disk rotor 21 is fixedly mounted on an inner end of drive shaft 17 and is born on the inner surface of front end plate 11 through a thrust needle bearing 22 which is disposed concentric with the drive shaft 17. The disk rotor 21 is provided with a drive pin 23 projecting on the rear surface thereof. The drive pin 23 is radially offset from the drive shaft 17 by a predetermined length.
Reference numerals 24 and 25 represent a pair of interfitting orbiting and fixed scroll members. The orbiting scroll member 24 includes an end circular plate 241 and a wrap means or spiral element 242 affixed onto one end surface of the end plate. End plate 241 is provided with a boss 243 projecting on the other end surface thereof. Drive pin 23 is fitted into the boss 243 with a radial needle bearing 26 therebetween, so that orbiting scroll member 24 is rotatably supported on drive pin 23.
A hollow member 27 having a radial flange 271 is fitted onto the boss 243 non-rotatably by means of key and keyway connection. The radial flange 271 is supported on the rear end surface of disk rotor 21 by a thrust needle bearing 28 which is disposed concentric with drive pin 23. The axial length of the hollow member 27 is equal to, more than, the axial length of the boss 243, so that the thrust load from orbiting scroll member 24 is supported on front end plate 11 through disk rotor 21. Therefore, the rotation of drive shaft 17 effects the orbital motion of orbiting scroll member 24 together with hollow member 27. Namely, orbiting scroll member 24 moves along a circle of a radius of the length between drive shaft 17 and drive pin 23.
Means 29 for preventing orbiting scroll member 24 from rotating during the orbital motion is disposed between end plate 241 of orbiting scroll member 24 and radial flange 271 of hollow member 27.
Referring to Fig. 2 in addition to Fig. 1, the hollow member 27 comprises a cylindrical portion 272 having a rectangular outer contour, on which a rectangular slider member 291 is fitted slidable in a radial direction. The rectangular slider member 291 has a rectangular hole with one pair of parallel sides equal to one pair of parallel sides of the outer rectangle of cylindrical portion 272 and with the other pair of parallel sides longer than the other pair of sides of the rectangular cylindrical portion 272 by at least twice length between drive shaft 27 and drive pin 23. Accordingly, the slider member 291 is slidable on the hollow member 27 in a radial direction along the longer parallel sides of the rectangular,hole. The slider member 291 is also fitted into a ring like member 292 which is non-rotatably fixed on the inner surface of cylindrical body 13 of the compressor housing by key and keyway connection (shown at 293 in Fig. 2). The central hole of the ring like member 292 is a rectangular hole with one pair of parallel sides equal to one pair of parallel sides of the outer rectangle of the slider member 291 and with the other pair of parallel sides longer than the other parallel sides of the same outer rectangle by at least twice length between drive shaft 17 and drive pin 23, so that the slider member 291 may be slidable within the ring like member 292 in a radial direction perpendicular to the slide direction of it on the hollow member 27.
Accordingly, hollow member 27 is permitted to move in two radial directions perpendicular to one another and, therefore, moves along a circle as a result of movement in the two radial directions but is prevented from rotation. Therefore, the eccentric movement of drive pin 23 by the rotation of drive shaft 17 effects the orbital motion of orbiting scroll member 24 together with hollow member 27 without rotation.
In another.construction of the ring like member 292, the ring like member has a central hole permitting hollow member to axially pass therethrough and is formed with a depression in an end surface for receiving and slidably guide the slider member 291. This construction of the ring like member permits the ring like member itself to be thin.
The other fixed scroll member 25 also comprises an end circular plate 251.and a wrap means or spiral element 252 affixed on one end surface of the end plate. The end plate 251 is provided with a hole or a discharge port 253 formed at a position corresponding to the center of the spiral elements, and with an annular projection 254 on the rear end surface around the discharge port 253.
The rear end plate 12 is provided with an annular projection 121 on the inner surface thereof around the outlet port 15. The outer radius of the annular projection 121 is selected slightly shorter than the inner radius of the annular projection 254. The annular projection 121 is cut away along the outer edge of the projecting end to define an annular recess 122. An annular elastic material, for example, a rubber ring 30 is fitted into the annular recess 122 and is compressedly held between the interfitted annular projections 121 and 254, so that the fixed scroll member 25 is elastically supported on the annular projection 121 of the rear end plate. The rubber ring 30 serves as a seal for sealing off a chamber 31 defined by annular projections 121 and 254 from the interior space 131 of the compressor housing. The chamber 31 connects between outlet port 15 and discharge port of fixed scroll member 25.
The end plate 251 of fixed scroll member 25 is formed with a plurality of cut away portions 255 at the rear end peripheral edge. A plurality of projections 132 are formed on the inner surface of cylindrical body 13 of the compressor housing and are mated into the cut away portions 255, so that the fixed scroll member 25 is non-rotatably disposed within the compressor housing. There is maintained gaps 32 between inner wall of the cylindrical body 13 and the peripheral end of the fixed scroll member 25, and, therefore, a chamber portion 33 surrounding annular projections 121 and 254 does not form a sealed off chamber within the interior space 131 of the compressor housing. The chamber portion 33 communicates with inlet port 14.
In operation, when drive shaft 17 is rotated by an external drive power source (not shown) through pulley 20, drive pin 23 moves eccentrically to effect the orbital motion of orbiting scroll member 24. The rotation of orbiting scroll member 24 is prevented by the rotation preventing means 29. The orbital motion of orbiting scroll member 24 compresses the fluid introduced in the interior space 131 through inlet port 14, chamber portion 33, and gaps 32, and the compressed gas is discharged from the outlet port 15 through discharge port 253 and the chamber 31.
Referring to Figs. 3a-3d, the introduced fluid is taken into fluid pockets 1 and 2 (which are shown at dotted regions) which are defined by line contacts between orbiting spiral element 242 and fixed spiral element 252, as shown in Fig. 3a. The line contacts shift by the orbital motion of orbiting spiral element 242 and, therefore, fluid pockets 1 and 2 angularly and radially move toward the center of spiral elements and decrease their volume, as shown.in Figs. 3b-3d. Therefore, the fluid in each pocket is compressed. When orbiting scroll member moves over 360 to the status shown in Fig. 3a, fluid is again taken into new formed fluid pockets 1 and 2, while old pockets connected together to form a reduced pocket and the already taken and compress-. ed fluid is discharged from the pocket through discharge port 253.
In the arrangement as above described, since fixed scroll member 25 is axially urged toward orbiting scroll member 24 by the restoring force of compressed rubber ring 30, sealing between end plate 241 of orbiting scroll member 24 and the axial end of fixed spiral element 252, and between end plate 251 of fixed scroll member 25 and the axial end of orbiting spiral element 242 is secured. And the sealing is reinforced by a fluid pressure discharged into the chamber 31. The axial load for securing the sealing is supported on disk rotor 21 through orbiting scroll member 24, hollow member 27 having radial flange 271, and thrust bearing 28, and is further supported through the disk rotor 21 and thrust bearing 22 on front end plate 11 which is secured onto front end of cylindrical body 13 of compressor housing. Therefore, any deflection of moving parts is prevented during operation of the compressor, so that the vibration of compressor and abnormal wearing of each parts may be prevented. Since disk rotor 21 fixedly mounted on drive shaft 17 is supported through thrust bearing 22 on front end plate 11, drive shaft 17 is securely and non-vibratingly supported by the use of a single needle bearing as a radial bearing.
The radial sealing force at each line contact between fixed and orbiting spiral elements 252 and 242 is determined by the radius of the orbital motion of orbiting scroll member 24 or the offset length between drive shaft 17 and drive pin 23, and the pitch and thickness of each of fixed and orbiting spiral elements 252 and 242. In practical use, the distance bet_'.veen drive shaft 17 and drive pin 23 is preferably selected slightly larger than the half of the dimensional difference between the pitch of each spiral element and the total dimension of thickness of fixed and orbiting spiral elements. This arrangement is permitted by the fact that fixed scroll member 25 is radially movably supported by the compressed rubber ring 30. The sufficient radial seal is established, even at the initial use of the compressor as assembled. The reasonable radial seal is completed after contact surfaces of both spiral elements wear by friction during use to get to fit to one another.
In the arrangement of the compressor as above described, assembling operation of the compressor is very simple; annular elastic material 30, fixed and orbiting scroll members 25 and 24, rotation preventing means 29,_' hollow member 27, bearings 26 and 28, and a pre-assembly of drive pin 23, disk rotor 21, bearings 16 and 22, drive shaft 17 and front end plate 11, are inserted in this order into cylindrical body 13 having rear end plate 12, and the compressor is completed by securing the front end plate 11 onto the cylindrical body 13 by bolt means 34.
The compressor in Fig. 1 has a lubricating system. The cylindrical body 13 of compressor housing is formed with an oil deflector 133 depending from the inner wall thereof into the interior. The front end plate 11 is provided with an oil opening 111 formed in the inner surface adjacent the oil deflector 133 and is also provided with an oil passageway 112 formed therein and effecting comminicate between the oil opening 111 and the shaft seal cavity 181 within the tubular portion 18.
The lubricant oil contained within the compressor housing is splashed by moving parts such as disk rotor 21 during the operation of the compressor and attaches onto, and flows along, inner wall of the cylindrical body 13 and parts assembled therein. Thus, the moving parts are lubricated. The oil flowing along the inner wall is directed by the oil deflector 133 into the oil opening 111 and flows therefrom through the oil passageway 112 into the shaft seal cavity 181.
The oil deflector 132, oil opening 111 and oil passageway 112,per se are similar to those in the lubricating system disclosed in U.S. Patent No. 4,005,948.
The oil which flows into the shaft seal cavity 181 returns to interior space 131 of the compressor housing after lubricating radial needle bearing 16, gap between front end plate 11 and disk rotor 21, and thrust needle bearing 22.
Another oil passageway 35 is formed through drive shaft 17 and drive pin 23, which effects communicate between the shaft seal cavity 181 and the inner space within the boss 243. So that the oil in the shaft seal cavity 181 partially flows into boss 243 and, therefrom, flows into the interior of the compressor housing after lubricating radial bearing 26, gap between disk rotor 21 and radial flange 271, and thrust bearing 28.
The distance r of one end of the oil passageway 35 within shaft seal cavity 181 from the central axis of the drive shaft 17 is advantageously shorter than the distance R of the other end from the same central axis. Since the centrifugal force at one end opening of oil.passageway 35 within the shaft seal cavity 181 is smaller than that at the other end opening within the boss 243, the lubricant oil readily flows into boss 243.
Means for restricting the oil from flowing through the gap between disk rotor 21 and front end plate 11, for example, an 0-ring 36 is disposed within the gap. Thus, the oil amount flowing through radial bearing 26 in the boss 243 is increased. In place of the 0-ring 36, a plastic ring with a square cross-section may be used. The plastic ring is disposed in an annular groove formed in either front end plate surface or rotor disk surface.
In order to separate the oil mixed in the refrigerant gas introduced through inlet port 14, a plate member 37 is fixedly disposed in front of the inlet port 14 within the annular chamber portion 33. The mixture of the oil and refrigerant gas strikes against the plate member 37 and the oil attaches onto the plate member 37. The separated oil drops from the plate member 37 and flows down along the inner wall of the chamber portion 33. The end plate 251 of fixed scroll member 25 and ring like member 292 are provided with oil holes 256 and 294, respectively, at the lower portion. Thus, the lubricant oil stays at the lower portion within the compressor housing.
Referring to Fig. 4, another embodiment shown which is a modification of the previous embodiment, is characterized in that end plate 251 of fixed scroll member 25 is closely fitted into cylindrical body 13 of the compressor housing with an 0-ring 38 being disposed between the inner wall of the cylindrical body 13 and the peripheral end of the end plate member 251. Accordingly, 'the chamber portion 33 forms a sealed chamber in the interior space 131. Therefore, the end plate member 251 is formed with another fluid passing hole 257 at the upper portion. Thus, the fluid introduced into chamber portion 33 through inlet port 14 flows into interior space 131, through the hole 255 and is taken into the fluid pockets between interfitting spiral elements 242-252.
In the arrangement of this embodiment, since such projections 132 as in the previous embodiment is not required to be formed on the inner surface of the cylindrical body 13, the cylindrical body 13 is easily made.
In the embodiment shown, the rear end plate 12 is formed not integrally with but separately from the cylindrical body 13, and is secured onto the cylindrical body 13 by bolt means 39.
A further embodiment of this invention as shown in Figs. 5 and 6 is another modification of the embodiment in Fig. 1 and is characterized in that a head block 40 including a discharge chamber 41 and suction chamber 42 is mounted onto rear end plate 12 and secured thereto by bolt means 43.
The discharge chamber 41 and the suction chamber 42 are separated by partitioning wall 401. These chambers 41 and 42 communicate with chambers 31 and 33 through outlet and inlet ports 15 and 14, respectively. The head block 40 is also provided with an inlet connector tube 44.and an outlet connector tube 45 which communicate with suction chamber 42 and discharge chamber 41, respectively. These connector tubes are connecting the compressor 10 with the refrigerant circulating circuit of a cooling system.
In this embodiment, the refrigerant gas is introduced into the suction chamber 42 from the refrigerant circuit through the inlet connector tube 44, and, therefrom, flows into the interior space 131 of the compressor housing through inlet port 14, and chamber 257. The compressed refrigerant gas discharged from discharge port 253 flows into discharge chamber 41 through chamber 31 and outlet port 15, and, therefrom, circulates to the refrigerant circuit through outlet connector tube 44.
The lubricating oil mixed with the introduced refrigerant gas is separated by an oil separating plate 37' which is fixedly disposed against inlet port 14 within suction chamber 42. The separated oil flows along the inner wall of suction chamber and flows into the interior space 131 of the compressor housing through an oil hole 123 which is formed in the rear end plate 12 at a lower portion thereof.
In a further embodiment as shown in Figs. 7-9, the compressor is provided with means for leaking compressed gas during the operation of the compressor at an increased speed, and is, thus, useful for a refrigerant compressor of an air conditioning system for an automobile wherein the compressor is driven by the automobile engine.
In Figs. 7 and 8, the similar parts are represented by the same reference numerals as the embodiment in Fig. 1. Drive pin 23 is provided with a hole 231 formed in the axial end thereof. End plate 241 of orbiting scroll member 24 is formed with a round depression 244 in the surface against the axial end of the drive pin 23 and is also formed with a small aperture 245 at the center of the round depression. A ball 46 is received in the round depression 244, and a compressed coil spring 47 is disposed in the hole 231 to urge the ball 46 to the center of the round depression 244. Accordingly, the small aperture 245 is closed by the ball 46. During the operation of the compressor 10, the ball 46 is subjected to the centrifugal force. When the rotating speed of drive shaft increases, and when the centrifugal force overcomes the force due to the coil spring 47 which positions the ball 46 at the center of the round depression 244, ball 46 moves from the center of the depression toward the peripheral end to open the small aperture 245. Accordingly, .compressed gas in a moving fluid pocket leaks through the aperture 245 in the interior 131 of the compressor housing, when the moving fluid pocket communicates with the small aperture 245. Therefore, when the drive shaft 17 is driven at an increased rotational speed, the compressed gas amount discharged from the outlet port 15 is decreased. Thus, the compressing capacity, that is a gas amount compressed in a unit time, is not so different between a'higher speed and a lower speed operation of the compressor.
The fluid leaking means for leaking compressed fluid at a high speed operation may be disposed not on an axis of drive pin 23 but at the other portion of-the orbiting scroll member 24.
In Fig. 9, the fluid leaking means is disposed at a position indicated at A in Fig. 7. Slider member 291 and ring like member 292 are partially cut away to form a space 48 adjacent the end plate 241 of orbiting scroll member 24. A bracket 49 is disposed within the space 48 and is fixed to the end plate 241 by means of, for example, welding. In the bracket 49, a coil spring 47' is supported, which, in turn, urges a ball 46' toward the end plate 241. The end plate 241 is also formed with a round depression 244' for receiving the ball 46' therein and a small aperture 245' at the center of the round depression.
This invention has been described in detail in connection with preferred embodiments, but these are merely for example only and this invention is not restricted thereto. It will be easily understood by those skilled in the art that the other variations and modifications can be easily made within the scope of this invention.

Claims

1. A scroll-type fluid compressor unit comprising a compressor housing having a front end plate and a rear end plate, a fixed scroll member fixedly disposed within said compressor housing and having first end plate means to which first wrap means are affixed and an orbiting scroll member orbitably disposed within said compressor housing and having second end plate means to which second wrap means are.affixed, said first and second wrap means interfitting at a predetermined angular relationship to make a plurality of line contacts to define at least one sealed off fluid pocket which moves with reduction of volume thereof by the orbital motion of said orbiting scroll member, thereby to compress the fluid in the pocket, wherein a drive shaft is supported by first radial bearing means in said front end plate and extends outwardly through said front end plate, a disk rotor member is mounted on an inner end of said drive shaft and is supported by first thrust bearing means on an inner surface of said front end plate, a drive pin projects axially on a rear surface of said disk rotor member and is radially offset from said drive shaft, said orbiting scroll member is provided with an axial boss which is formed on a surface of said second end plate member opposite to said second wrap means and is rotatably mounted on said drive pin which is fitted into said boss through second radial bearing means, a radial flange member is radially extending and is disposed at the projecting end of said axial boss and is supported by second thrust bearing means on the rear surface of said disk rotor member, and means are provided for preventing the rotation of said orbiting scroll member, but permitting the orbital movement of said orbiting scroll member.

2. A unit as claimed in Claim 1, wherein said rotation preventing means comprises a hollow member which has a rectangular outer contour and is non-rotatably fitted onto axial boss, a slider member is fitted on said hollow member so as to be slidable in a first radial direction and has a rectangular hole and a rectangular outer contour with four sides parallel to respective four sides of said rectangular hole, a first pair of parallel sides of said rectangular hole being equal in length to a pair of parallel sides of the outer rectangle of said hollow member and the other second pair of parallel sides of said rectangular hole being longer than the other pair of parallel sides of said hollow member so that said slider member may be slidable on said hollow member along said second second pair of parallel sides, and a guide member non-rotatably disposed within said housing and having guide surfaces for respective parallel outer surfaces of said slider member in parallel with said first pair of parallel sides to permit the movement of said slider member in a second radial direction perpendicular to said first radial direction, thereby to permit the orbital movement, but prevent the rotation, of said orbiting scroll member.

3. A unit as claimed in Claim 2, wherein said hollow member is provided with said radial flange formed integrally therewith.

4. A unit as claimed in Claim 1,2 or 3, wherein said rear end plate of said compressor housing is provided with fluid inlet and outlet ports, a first annular wall projects axially on the inner surface of said rear end plate around said fluid outlet port, said fixed scroll member is provided with a fluid discharge port at a center of said first end plate means, a second annular wall projects axially on a surface of said first end plate means opposite to said first wrap means around said fluid discharge port, said first and second annular walls being fitted into one another to define a chamber therein, and a sealing ring member of elastic materials seals off said chamber from the interior space of said compressor housing and is compressedly fitted into a gap between said first and second annular walls thereby to axially and radially elastically support said fixed scroll-member.

5. A unit as claimed in any one of Claims 1 to 4, wherein the distance from said drive shaft to said offset drive pin is so selected that the radius of the orbital motion of said orbiting scroll member is slidably larger than one half of the dimensional difference between the pitch of said first wrap means and the total dimension of thickness of said first and second wrap means, whereby the sealing effect of said fluid pocket may be secured at said line contacts.

6. A unit as claimed in any one of Claims 1 to 5, which further comprises an oil deflector depending from the inner wall of said compressor housing thereinto, said front end plate being provided with a shaft seal cavity around said drive shaft and including an oil opening disposed adjacent said oil deflector and a first passageway formed therein effecting communication between said oil opening and said shaft seal cavity, and a second passageway extending through said drive shaft and said drive pin and effecting communication between said shaft seal cavity and the hollow space of said boss, whereby oil on the inner wall of said compressor housing is directed by said deflector through said oil opening and into said shaft seal cavity, said oil in said shaft seal cavity partially flowing through the gap between said front end plate and said disk rotor member and lubricating said first radial and thrust bearing means, with the remainder flowing through said second passageway into the hollow space of said boss to lubricate said second radial and thrust bearing means.

7. A unit as claimed in Claim 6, wherein the distance of one end of said passageway in said shaft seal cavity from the central axis of said drive shaft is shorter than the distance of the other end from said central axis.

8. A unit as claimed in Claim 6, wherein means for restricting oil flow are disposed within the'gap between said disk rotor member and said front end plate.

9. A unit as claimed in any one of the preceding Claims, wherein said second end plate means of said orbiting scroll member is provided with a round depression in a surface thereof opposite to said second wrap means and a small aperture at the center of said round depression, a ball is received in said round depression to close said aperture, and spring means urge said ball in said round depression. 10. A unit as claimed in Claim 4, wherein said first end plate means is formed with a plurality of cut away portions at the rear end peripheral edge, said compressor housing is formed with a plurality of radial projections on the inner surface thereof, said radial projections mating with said cut away portions to prevent said fixed scroll member from rotating, an annular chamber portion is defined within said interior space of said compressor housing which surrounds said first and second annular projections and connects with said inlet port, and a plurality of gaps is defined between the inner surface of said compressor housing and the peripheral end of said first end plate means and between adjacent said radial projections to connect said annular chamber portion with the remaining interior space of said compressor housing, whereby fluid is introduced from said inlet port into said interior space of said compressor housing.

11. A unit as claimed in Claim 4, which further comprises an 0-ring tightly disposed between the peripheral end of said first end plate means of said first scroll member and the inner wall of said compressor housing, an annular chamber portion being defined within said interior space of said compressor housing which surrounds said first and second annular projections and connecting with said inlet port, and said first end plate means of said fixed scroll member being provided with a suction port at a peripheral portion thereof to connect said annular chamber portion with the remaining interior space of said compressor housing, whereby fluid is introduced from said inlet port into said interior space of said compressor housing.

12. A unit as claimed in Claim 10 or 11, wherein a plate member is disposed in front of said inlet port within said annular chamber portion to separate oil from the gas introduced through said inlet port.

13. A unit as claimed in Claim 4, which further comprises a compressor head block having a suction chamber and a discharge chamber and mounted on said rear end plate, said rear end plate being provided with a hole effecting communication between said suction chamber and said annular chamber portion surrounding said first and second annular walls, said discharge chamber being connected with said outlet port, and a plate member being disposed within said suction chamber and for separating oil from the gas introduced into said suction chamber.